1. Field of the Invention
The invention relates generally to improved reinforced concrete pilings and more particularly to a round piling having front and back flat portions and a method of manufacturing the pilings.
2. Discussion of the Prior Art
Wood piles are subject to destruction by various causes and especially piles used in a marine environment where water and marine life are particularly destructive. To preserve wooden piles, various types of pre-treatment have been used, however, with the restrictions of environmental laws, several of the most effective preservatives have been banned.
Concrete piles are less destructible and, hence, are adapted to many conditions. Piles may be driven by the drop hammer or steam hammer methods. The steam hammer, with its comparatively light blows delivered in rapid succession, is of advantage in a plastic soil, the speed with which the blows are delivered acting to prevent the readjustment of the soil. It is also of advantage in soft soils where the driving is easy, but a light hammer may fail to drive a heavy pile satisfactorily. A water jet is sometimes used in sandy soils. Water supplied under pressure at the point of the pile through a pipe or hose run alongside it erodes the soil, allowing the pile to settle into place. To have full capacity, jetted piles are driven after jetting stops.
Piles may obtain their supporting power from friction on the sides or from bearing at the point. In the latter case, the bearing power may be limited by the strength of the pile, considered as a column, to which, however, the surrounding soil affords some lateral support. In the former case, no precise determination of the bearing power can be made.
Concrete piles may be divided into two classes, those which are molded in place and those which are pre-cast, cured and driven. Piles of both types, longer than 100 feet, have been driven. In one well known pile of this type, a thin sheet is fitted over a tapered mandrel before driving. This shell, which is left in the ground when the mandrel is withdrawn, is filled with concrete. Another well known pile of the molded-in-place type uses a hollow cylindrical mandrel which is filled with concrete after having been driven to the desired depth and raised a few feet at a time, the concrete flowing out of the bottom and filling the hole in the earth. Pre-cast and molded-in-place piles may be reinforced with steel. Only steel-reinforced piles are of interest in this invention.
Several prior art inventions have tried several methods to cast reinforced piles, such as, for example U.S. Pat. No. 1,393,545 to Knuth discloses a concrete piling including a tube extending the entire length of the pile through which tube a stream of water may be forced to issue at the lower end of the pile. The piling is reinforced with a series of vertically disposed metallic rods. In order to adapt the construction for use in sheet piling by forming longitudinal, V-shaped grooves are opposing each other. The spaces are then filled with concrete in situ or wooden timbers are forced into the spaces to make the joints water proof.
U.S. Pat. No. 1,163,377 to Selfridge discloses a concrete pile form comprising a spirally wound paper tube arranged vertically and engaging at its bottom a conical metallic shoe which forms the driving point of the pile. A plurality of anchor rods extend up into the tube and become embedded in the concrete. The reinforcing rods are tied to the anchor rods to produce a stronger structure. Cast into and extending through the shoe is a conduit which opens at the bottom of the shoe. Arranged within the form and connected to the conduit is a pipe which projects through the paper tube adjacent its upper end, the tube being provided with reinforcement at the point at which the pipe passes through. When the pile is being driven, water is forced through the pipe to loosen the earth in advance of the pile.
U.S. Pat. No. 1,165,134 to Schlueter discloses a pile consisting of a shaft, a head, and a continuous groove being formed along the inner side of the column having an enlarged area near the base. Longitudinal reinforcing rods are vertically located in the column and are tied together at suitable intervals by horizontal ties. The horizontal tie consists of a long member running around outside of all of the vertical reinforcements and a series of short rods and tying the vertical reinforcements together in pairs.
U.S. Pat. No. 4,317,543 to Miller discloses a reinforced concrete pile having a plurality of steel reinforcing cables and at least one ferrous metal alloy electrically conductive rod per cable which permits severing by oxygen cutting or electric arc welding.